A handheld GPS receives extremely accurate position information from an array of 24 satellites that orbit the Earth. According to Garmin, their GPS devices are accurate to within 50 feet. GPS devices cannot only be used in automobiles for driving directions, but also on foot while hiking. A person walking can use a GPS to determine the dimensions of a large shape or tract of land outdoors by noting the distance travelled.

- Skill level:
- Moderate

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## Instructions

- 1
Turn on the GPS and set it to "Walking" mode. Set the display to show the distance travelled on this trip. Assume you are attaining the area of a rectangular stretch of land.

- 2
Walk the length of the land area then note the distance travelled on the GPS in miles. Walk in a straight line by keeping the same cardinal direction on the GPS throughout the walk. For example, the distance might be 1.4 miles north.

- 3
Walk the width of the land area, keeping a straight bearing, and note the total distance travelled for the trip. For example, the trip distance may be 3.2 miles.

- 4
Subtract the length from the total trip distance to obtain the width in miles. Now you have 3.2 miles minus 1.4 miles, which equals a width of 1.8 miles.

- 5
Multiply the length times the width to get the area of the land in cubic miles. Completing the exercise leads to 1.4 miles times 1.8 miles, or 2.52 square miles.

#### Tips and warnings

- Other shapes may be accounted for by walking the appropriate dimensions and noting the distances. Then use the appropriate geometrical formula for the shape to attain area.